Cyclura stejnegeri

Mona Rhinoceros Iguana


Range: Isla Mona, Puerto Rico
Population: 4000-5000
Size: 3-4ft total length
Threats: Invasive mammals.

species Information

  • This Critically Endangered Species is found only on the island of Mona, a protected area midway between the islands the islands of Puerto Rico and Hispaniola but not part of the Puerto Rican or Hispaniolan Bank. 
  • Mona is a dry subtropical island and iguanas make use of the limes rock topography which offers many underground shelters.
  • The biggest threat to this iguana is invasive species such as cats, rats, goats, and pigs, the latter especially target nesting areas and consume up to 100% of eggs. Nesting areas are also heavily impacted by flooding.
  • A head start program was initiated in 2000 and has to date released 263 iguanas into the wild. This has increased the population of wild adult iguanas and boosted the recruited of juveniles.
  • The conservation focus now is to eradicate invasive mammals on the island and restore habitat and nesting grounds.

Mona Rhinoceros Iguana

IIF Grants Received

2019 Grant $5,500

Reassessment of headstarting initiatives and population status of the Mona Island Iguana.

Nestor Perez-Buitrago


2005 Grant $6,000

Development of a Cost-Efficient and Effective Monitoring Program for the Mona Iguana Population

Nestor Perez-Buitrago, Stephan M. Funk, W.O. McMillan, and Miguel Garcia


This IIF grant funds a feasibility study for using non-invasively collected DNA samples (from feces) as a tool for acquiring accurate population estimates. Using existing density estimates on the Mona Iguana population, workers will compare conventional field methods (mark-recapture) with modern lab techniques using genetic markers. This pilot project has long-term implications for field assessments of other endangered iguanas.